Properties of viologen-TCNQ (2-2) Langmuir-Blodgett films

Abstract

In conducting systems based on Langmuir-Blodgett(LB) films, TCNQ derivatives have been extensively studied as electron acceptor molecules. We have investigated the optical, electrical, and magnetic properties of viologen-(TCNQ(-))(2) LB films. In UV/visible absorption measurements, we have observed TCNQ(-) peak at 381 nm and dimer peak at 626 nm. Iodine doping affects the degree of charge transfer and increases the conductivity of the films. The UV/visible absorption spectra of the LB films doped with I-2 show a peak at 400 similar to 430 nm and there is no dimer absorption peak. The electron spin resonance (ESR) measurements infer that the viologen-(TCNQ(-))(2) LB film exhibits anisotropic property. In other words, the ESR signal of the LB film shows angular dependence. The in-plane electrical conductivity of the undoped film is approximately 4.3 x 10(-6) S/cm at room temperature.